Many industrial processes and machines are controlled and/or powered by electric motors. Motorized systems include pumps providing fluid transport for chemical and other processes, fans, conveyor systems, compressors, gear boxes, motion control devices, screw pumps, and mixers, as well as hydraulic and pneumatic machines driven by motors. Such motors are combined with other system components, such as valves, pumps, conveyor rollers, fans, compressors, gearboxes, and the like, as well as with appropriate motor drives, to form industrial machines and actuators. For example, an electric motor may be combined with a motor drive providing electrical power to the motor, as well as with a pump, whereby the motor rotates the pump shaft to create a controllable pumping system.
Controls within such motorized systems provide for automatic system operation in accordance with a setpoint value, and may additionally allow for manual operation. Thus, for instance, a motorized pump system may be operated so as to achieve a user specified outlet fluid flow rate, pressure, or other system setpoint. In another example, a motorized conveyor system may include one or more motorized roller systems, wherein the individual roller systems are controlled according to a conveyor speed setpoint. Such motorized system controls may include a controller receiving a setpoint from a user or from another system, which inputs one or more system performance values and provides appropriate control signals to cause the motorized system to operate in a controlled fashion according to a control scheme. For example, a motorized pump system may be controlled about a flow rate setpoint, wherein the associated controller reads the setpoint from a user interface, measures the system outlet flow rate via a flow sensor, and provides a control signal indicative of pump speed to a motor drive operatively connected to a motorized pump, whereby the control signal is adjusted so as to achieve the setpoint flow rate in closed-loop fashion.
Although operation of such motorized systems and controllers may achieve system operation in accordance with the setpoint, other factors such as system component wear, component faults, or other adverse conditions, and the like, may affect the operation of the motorized system. Thus, for example, degradation in a pump impeller in a motorized pumping system may lead to premature catastrophic failure of the system if left unchecked. In this regard, operation of the pump strictly in accordance with a flow rate setpoint may accelerate the system component wear, degradation, and/or failure, whereas operation at other flow rates may allow the system to last longer. This may be of importance in critical systems where safety is an issue. For instance, the motorized pumping system may be located on board a military vessel at sea, wherein operation according to a flow setpoint may lead to catastrophic pump impeller or seal failure before the vessel can be brought to port for repairs or maintenance, whereas system operation at a reduced flow rate may allow the pump to survive until the next scheduled servicing.
Motor diagnostics apparatus has been employed in the past to provide an indication of wear, damage, and/or degradation in motor system components, such as rotors, bearings, or stators, prior to catastrophic failure thereof. Such diagnostic devices may be used to monitor the overall health of either the motorized system components being controlled, or the control system itself. In this regard, assessing system health can be used to minimize unscheduled system downtime and to prevent equipment failure. This capability can avoid a potentially dangerous situation caused by the unexpected outage or catastrophic failure of machinery. However, many conventional diagnostic devices inconveniently require an operator to manually collect data from machinery using portable, hand-held data acquisition probes.
Other known systems have sensors and data acquisition and network equipment permanently attached to critical machinery for remote diagnostics. Typically the diagnostics equipment is directed to detecting problems with the process control system hardware itself or monitoring the integrity of the output, i.e., monitoring when the process response is outside prescribed time or value limits. As noted above, system health monitoring, health assessment and prognostics generally are performed in isolation from any associated control system. These systems typically conduct passive monitoring and assess system health using diagnostic algorithms and sensors dedicated to establish system health. This passive monitoring is frequently done using off-line, batch-mode data acquisition and analysis to establish the health of the system.
In conventional motorized systems, therefore, controlled operation is provided about a setpoint, wherein such controlled setpoint operation may exacerbate system component degradation and/or accelerate catastrophic failure thereof. Prior diagnostics apparatus achieves some level of identification of such system component degradation prior to component failure. However, as noted previously, because virtually all diagnostics systems perform off-line diagnostic processing, it has been extremely difficult to implement diagnostics processing real-time in coordination with on-line control. Thus there is a need for improved control and diagnostics systems and techniques by which controlled operation of motorized systems can be achieved while mitigating the extent of component degradation and failure.